|
[Sponsors] |
July 31, 2007, 11:44 |
problem pure diffusion
|
#1 |
Guest
Posts: n/a
|
Hi, I have a cylindrical domain (1 mm diameter, 5mm length) with opening boundaries defined at the two opposing faces. The value for an additional variable is 1 kg/m3 inside the channel and 0 kg/m3 at the opening boundaries. I have defined water 25C as my fluid inside the channel and switched on kinematic diffusivity for the additional variable with value of 0.5e-5 cm2/sec. There is no convection. I do a transient run with total simulation time 30 sec. At t = 30s, I see not even a slight change in concentration at the edges, i.e. no diffusion out of the domain seems to take place. Anyone a suggestion what I do wrong here?
Thanks, Jorn |
|
July 31, 2007, 11:53 |
Re: problem pure diffusion
|
#2 |
Guest
Posts: n/a
|
Dear Jorn,
What type of Additional Variable are you using Poisson, Diffusive, or Transport Equation? By default, CFX does include diffusion at inlets/opening/outlets for the Transport Equation option.. Hope this helps, Opaque |
|
July 31, 2007, 11:56 |
Re: problem pure diffusion
|
#3 |
Guest
Posts: n/a
|
I'm using the transport equation option... Jorn
|
|
July 31, 2007, 12:06 |
Re: problem pure diffusion
|
#4 |
Guest
Posts: n/a
|
Ok I see now what went wrong... in the 30 sec. the effect of diffusion is small and the mesh at the opening boundaries was too coarse to resolve this.
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Gambit - meshing over airfoil wrapping (?) problem | JFDC | FLUENT | 1 | July 11, 2011 05:59 |
FVM for diffusion problem or dispersive problems? | Wen | Main CFD Forum | 0 | February 22, 2006 13:34 |
Diffusion problem | ravi varma | FLUENT | 6 | December 8, 2002 23:10 |